Corrosion inhibited composition



United States Patent 2,992,081 r QR Q Q COM OS O vid B- Sheldah .G'iifith, Ind an h a .0. Co n s,

,PalikfFores t,' lll assignors to 'Sinclair Refining Comapany,'. NewYork,-N. Y,, a corporafion of Maine Nd'Drawing; Fild-JulySO, 1957,'Ser.No. 675,016 (Cl. 4'4--1'66) This invention relates to new. compositionsof matter :and more particularly i-to ;a new class :of chemical ,corn--pounds derived from theireaction {Qfgfi monocarbo rylic aoid, a fattyamido diamine :and an aromaticsulfonic acid. ln other aspectsu thisinvention relates-to novel :compositions of matter and their use as aoorrosion-inhibitor in liquid mineral .oils which normally come incontact uw-ith :metals.

Various corrosion inhibitors have been suggested 'for :use in liquidmineral oil bases :for :theprotection of1 netal surfaces, :both:internal andex-ternal, which-come in contact with'the :base oils. Manyof .these inhibitors when included in distillate fuels,for example,'haveproved disadvantageous 1 inasmuch as sfilms produced :therefrom do not.exhibit sufiicienttresistance to moisture, iparticularly -under highhumidity .conditions. :.In many applications, as in diesel engineZflushing fuels, for iexample,':the base toil must be inhibited against:corrosion under high :husmidity conditions and atxthe same time sit isdesirable, land in fact some specifications require, that the inhibitor-be ashlsss. 1

" In accordance with this invention we have found that -corrosionproblems occurring from tmineral oils contact- :ing metallic surfacescan be materially lessened through ;use .of novelpcorrosioninhibitorsprepared by .reacting certain fatty" amide diamines,monocarboxylic 'acids .and aromatic sulfonic acids. The inhibitorproducts are identiified. as mono-sulfonatefattyamido diamineasaltsofmono- .carboxylic .ac'ids:andfi.as shown hereinafter, these reactionproducts have been-found;to.exhibit marked protecifiOIL of metalsurfaces, particularlyierroussurfaces, :which ;are in contact [withliquid mineral oil :products containing small amountsofnnois'ture.*When'blended'dn mineral .:oil :pro dllOtSrSllCh a'sgasoline and .dieselfuel, such 'ifuels easily pass humidity -cabinet corrosion :tests which-thus indicates their 're'sistanceito .moisture=under high humidityconditions. "Moreover,.-the inhibitors :give protection :in static anddynarnic' systems, e.g.storagetanks and pipelines. The novel inhibitorproducts 3 of this invention effectively prevent corrosion --withoutinfluencing basic ;cl iaracteristics of the mineral oil products inwhich they ;are incorporatdand are further advantageousjn that theywill, not form a combustion ash upon being subjected at vely hi hit mp aure it I'The corrosion inhibi in composi ion o thi i en- 2,992,08 1,Patented July 11, 1 96.1

in w i R a R1 r p sen cn a e h dr ca bon radicals containing from about6 to22 carbon. toms, 1R

is the aromatic hydrotcarbon radical derived fr ,m c s l o s, an R3 ndRtr valent, In hydrocarbon radicals, each of about 2 to 8 carbqnatoms,branched or straight ,chained and substituted or unsubstituted. Thegroups R and R may beali-keor ,diiierent, saturatedor-unsaturated,straight chainor branched may contain substituent groups such .as amino,halogen, hydroxy, nitrile, and the like and preferably' are;alipliatic.

The novel corrosion inhibiting compoundspf the present invention are themineral oil-compatible, 1i.e. .dis- ,persible, soluble or misciblewithout continuing agitaltion, materials identifiedas mono-sulfonatefatty ,amido diamine salts of monocarboxylic acids and can ,bepre-:pared, for-example, by reactinganaromaticsulfoniclacid andmonocarboxylic acid in stoichiometric amounts .with the fatty amido,diamine. The reactionis almost ,instan- .taneous it carried out at atemperature betweeni abou t 10010 F. but will occur slowly at ,room.te1npera- :ture. If desired, the reaction may be etfectedwvithli ht:aid of a solvent or at higher temperatures below .the decompositionpoint of the reactants or products- Advantageonsly, :as shownhereinafter, more than ,thestoichio- .rnetricarnounts of thereactantscanbe employed; f o,r -,example, up to twice vas, ,much or more of thereactants ,can be present and the excess resulting from ithfi reac-.tion may be included with the principal .corrosion inhibiting salt whenadded to a mineral oil base.

The fatty .amido .diamines which are .used in accordance with theinventionare represented ,by gthe .fiollowing general .formula:

in which R is a hydrocarbon group containing at least about 6-andpreferably 12 to 22 carbon tatoms a nd R and 'R areasdescribed above.Preferably, R and R are polymethylene groups of about '2 to8'carbonatorns, advantageously 2 to 4 carbon-atoms. The members of thisclassof diamine compounds are cationic and'possess one primary andsecondary amine groupin addition to an acyl radical attached to theamide nitrogen. The acyl radical in the above formulamay be straight'or-branched chain, or alicyclic, may containsubstituent' groups such ashalogen, amino, hydroxy, nitrile, and the like, andis preferably analiphatic carboxylic acidresidue of {high 'molecular weight fatty acids,either saturated or unsaturated. Examples of such acids are oleic acid,stearic acid, palmiticacid, linoleic acid, linolenic acid, ricinol'eicacid, monohydroxy stearc acid, lauric acid, high molecular weightnaphthenic acids, fatty acidsobtained fromthe oxidation of petroleumwaxes, and the like. Fatty acids which are particularly desirablefor'providing the car- "boxylic acid residue can be obtainedfrcm-vegetableioils and animal -fats such as soybean oil, coconut o'il',lard oil, corn oil, castor oil, tallow, and the like. Other suitablecarboxylic acid residues having the desired number of carbon atoms arethe acids obtained from tall oil which contains a mixture of fatty acidsand resin acids.

The fatty amido diamines can be prepared by reacting a polyalkylenetriamine of the formula in which n is a number from about 2. to 8,preferably 2 to 4, with a carboxylic acid or a derivative thereof, suchas an ester, anhydride, or halide in such proportions and under suchconditions 'as to elfect monoacylation 'of one primary amino grouppresent in the polyalkylene triamine. Fatty'glycerides are examples ofesters that are good acylating agents, and particularly preferredmaterials are corn oil or tallow which provide a saturated andunsaturated aliphatic hydrocarbon group of from about 16 to 18 carbonatoms. The fatty amido diamine is prepared by reacting a ratio of 1 moleof fatty acid for each mole of polyalkylene triamine at a temperatureabove 250 F. and preferably at a temperature of about '300 to 350 F. Attemperatures below about 250 F.,

the reaction products will consist of salts of the polyalkylene triaminerather than the amide. Other methods of preparation which aresatisfactory include reaction of the desired fatty acid and polyalkylenetriamine with ammonia to obtain the corresponding amide. The amide isthen reacted twice with acrylonitrile with each reaction being followedby hydrogenation to produce the final fatty amido diamine product.

An example of a preferred fatty amido diamine used in the preparation ofthe corrosion inhibitors of this invention is a commercial productdesignated as Diarnine 257 which corresponds to the above fatty amidodiamine formula in which R and R are trimethylene and Ris the straightchain unsaturated hydrocarbon radical derived from corn oil and havingabout 16 to 18 carbon atoms. This product is well known and ischaracterized by having an acid number of less than 5, an average amineequivalent weight of 210, and one primary and secondary basic aminegroup. The product has an appearance of a viscous liquid or fluid pasteand has a density of 0.935 at 25 C.

The monocarboxylic acids which are used in the present invention arehigh molecular organic monocarboxylic acids of the formula R'-COOH inwhich R represents a hydrocarbon residue or radical containing about 6to 22 carbon atoms. The monocarboxylic acids may be straight chain orbranched chain, substituted or unsubstituted, saturated or unsaturated,and include such acids as capric acid, caproic acid, undecylic acid,lauric acid, myristic acid, ricinoleic, oleic acid, linoleic, stearicacid, palmit-ic acid, margaric acid, arachidic acid, mixtures of any twoor more of these acids or others, fatty acids derived from animal orvegetable sources, hydroxy and accordance with this invention are thosein which the hydrocarbon radical contains from about 12 to 18 carbonatoms, saturated or unsaturated, such as steanic acid,

linoleic acid and palmitic acid, with particular preference 7 beingdirected to oleic acid.

The sulfonic acid materials which can be used the .preparation of thecorrosion. inhibitors; of this invention are the aromatic; sulfonicacids including those derived from petroleum; products. 7 The usefulpetroleum sulfonic acidsthus include the water-solubleor-water-dispcrsible green acids and the preferentially oil-solubleacids referred to as mahogany acids. The green acids are found in theacid sludge resulting from the treatment of a suitable petroleum oilsuch as a liquid petroleum distillate boiling in the range of 600 to1000 F. with fuming sulfuric acid or sulfur trioxide, and are in factmixtures of water-soluble sulfonic acids known as black acids,intermediate detergent-type sulfonic acids, and oil-soluble sulfonicacids called brown acids. The green acids are hydrophilic in characterand can be recovered from the acid sludge by adding water to the sludgeto dilute the sulfuric acid thereinto a concentration of about 20 to 30percent, at which concentration the, green acids separate to form thesupernatant layer, or they can be extracted from the sludge by usingwater-soluble solvents. The mahogany acids, some of which show limitedhydrophilic properties, are oil-soluble or hydrophobic by nature and canbe recovered from the acid treated oil or obtained as a concentrate inthe acid oil varying from 10 to percent by weight. The useful mahoganyacids generally have a molecular weight of from about 300 to 500, ormore, and although their exact chemical structures may vary, it appearsthat such acids are composed to a large extent of sulfonated aromatichydrocarbons having either one or two-aromatic rings per moleculepossibly with one or more long-chain alkyl' groups containing from about8 to 30 carbon atoms attached to the ring nuclei.

Suitable sulfonic acids which include both the oil and water-solublepetroleum sulfonic acids are the aryl sulfonic acids, benzene sulfonicacids, cymene sulfonic acid,- naphthalene sulfonic acid, alkylatednaphthalene sulfonic acid, fatty sulfonic and fatty aromatic sulfonicacids. 7 Other useful aromatic sulfonic acids are. the oilsolubleammonia neutralized sulfonated mixtures of polyalkylated benzenes; alkylaryl sulfonic acids in which the 'alkyl chain contains from about 8 to'18carbon atoms;

fonic acids obtained by reaction of ammonia with sulfuric acid treatedhydrocarbon oils, ammonium sulfonates of the alkyl aryl sulfonic acids,particularly those having a monocyclic nucleus, all of which areavailable or may be readily prepared byknown methods. Particularlysuitable sulfonic acid materials are ammonia neutralized sulfonatedNeolene bottoms described in U.S. PatentNo. 2,671,757 tOlT. G. Wisherd,and the ammonium mahogany sulfonates described in U.S. Patent No.2,632,694 to F. M. Watkins. The aromatic. oil-soluble sulfonic acidsare'conveniently employed as a concentrate in the oil from which theyare .derived and are usually present as a 10 to 30 weight percentconcentration.

The monosulfonate fatty amido diamine salts of monocarboxylic acids ofthis invention are. effective in liquid petroleum hydrocarbons includinglight distillates,, i.e. liquid hydrocarbonsboiling up toand includinggas oils, and lubricating oils. As examples they can be employed ingasoline, kerosene, petroleum solvents, diesel fuels, heating oils,neutral oils, etc. .The amount employed in a given instance will dependupon the character of the base oil' and the degree of'corrosion'-inhibition desired with a small but suflicient amount being employedto give substantial corrosion inhibition. Generally, the inhibitor wilcomprise from about 0.001 to 5,0'weight percent or more of the totalcomposition with larger percent being preferred for flushingcomposi-tions, The corrosion-inhibitors ofthe present invention-maybeused alone or in combination with other additives such as anti-foamagents, detergent additives, pour depressants, viscosity indeximprovers, etc., which improve .the compos'itionin one ormore respects.Since *th'-mineraloil is: present in relatively large and major amountsthe optimum concentration 'ofiany "combinationofi. additivesv'vilhof'course, depend uponthe particular type-dfmineral oil base stockand the potency of theadditiv'e combination contained therein.

Ihe vfollowing specific examples will serve to illusirate .the presentinvention *but. they are not to belconsidered limiting. V I

Ascorrosion inhibitor of this invention was prepared bathe-followingmanner:

".ISlX parts by 'weightiof -,0 leic acid, 105 parts by weight f ?Diamin5 ;tand 813.15 :partsby -.We.igh. o.f m o ny .sulfonic acids.(ilovpercent solution ;i n its base ,petroleum oil; 300 SUS at 100 .F.,Acid No. 16.4) were reacted at a temperature of 100 to 120'"F. A clearhomogeneous sdlution resulted which was a '12'5 percent concentrate ofthe monosulfonate fatty amidoadiaminesaltof 'the oleic acid. Thesolution "had :the :following properties:

.Gravity, ,API 22:4 Viscosity, .SUS at 100 F. i658 Viscosity, .SUS ,at210 ,F., 765.7 :Flash, F.. r .370 Fire, F. .430 .Pour, F. Color, NPA 8-Acid mumber 1 1126.0 .Saponificationnumber 2.4.5

..Nitrogen, percent f. 1;0:7 -Sulfur, percent 0. 82

Gravity, API 23 .7 Viscosity, SUS at 100 451 Viscosity, SUSJat 210 F.60.5 Flash, -F. 350 LFiIe, F.. V .410 ,Pour, F. -'35 1Color, NPA i 7"Acid number 1126.5 Saponification number r l r r r ;-26.4 Nitrogen,percent 0.69 "Sulfur, percent e 081 In order to show the outstandingcorrosion, character- --i StiCSOfI1the:COHIPOIJHdSOI thissinventiom tthenovel in- ."ihibitoraszprepared in Example I :was; blendedwith-tdieselifuel 2 and subjected to zawhumiditya icabinet corrosion -.testridentified ;-as the ;MIL-L2;l260 type hpeeifieation fl ubrieating Oil,Internal Combustion Engine, ;Pr eservative). This test is carried out asfollows:

Small sand blasted mildSteel panels are dipped in the.

petroleum hydrocarbon and after draining two hours at roomtemperaturearesuspended:irmachighly humid atmosphere, generallyabout 100percent humidity, at 120 F. in a special cabinet. The time of initialcorrosion of the panels is noted. The humidity cabinet is provided-375with heating-"units and thermal regulators for automatic temperaturecontrol. A water level of 8 inches maintainedin the bottomof-thecabinetand 8 linear feet per hour of clean air is bubbled throughthe water to assure high humidity at all times. lhe astee'l panels aresuspended by stainless steel hooks around the periphery of the humiditycabinet. Aboutthree complete changes of air per hour are provided in thecabinet. In order to pass the test, no more 'than'3 rustspots l mm. 'indiameter should be observedon the panel after 6 days exposure in thecabinet.

.A summary of ithe humidity cabinet results obtained when using themonosulfonate fatty amido diamine salts -of- 'monocarboxylic acids as acorrosioninhibitor indiesel fuel is shown below. The diesel fuelemployedhadnn API gravity of 138.6, a boiling range of-370 to 640 E.

and an SUS viscosity of 35.6 .at l 00 Iheefiectiv ne .of thenovelinhibitor asprepared in .Examplel is revealed .by the number of days thepanel isexposedbeforeifailure occurred, and as compared to themono-sulfonate-mo'ncr .oleateqfatty .diamine of Example II, striking.difierence's protection for over nineteen vdays whereas the fattydiamine saltof Example H'was substantially less effective.

Table 1 MIL-b21260 'HUMIDLTY CABINET *[lJEST RESULTS .iOoncentraluOahlnet Inhibitor Percent sel Euel,

None None 11-,- 'Mono-oleate *Inonosulfonate salt of fatty 0. 46' 7amide diamine, as preparediniExampleiLt D259; 019.;5 Mono-oleatemono-sulfonate salt oi ,iatty 0.118 1 4 diamine, as prepared in Example'II. 0:69 6

1 Number of dayslbefore two or three'rust spots 1 mmu-ln-diameter:appear'on test pan The following data offiTable- IIillustr ate':theresults obtained when the compounds prepared -'in accordance with thepresent invention we're tested in mineral-oil products such as gasolineand diesel fuel for 'dynamic corrosion inhibition properties. Thereaction product of 'Example II, whichdoes notcontain the amide linkage,is

used for comparison purposes with-the-compositionof the presentinvention (Exainple I) Whic'h-en1ploys a fatty amidodiamine as=the*amine'constitue'nt. Theidynam'ic 'corrosiontest-isa modification-oftest D-665-47T for rust-preventing characteristics of steam turbine-oilin -the-presenceof water and is useful for determining-the protectionafiorded by 'corrosioninhibitors under dynamic conditions, e.g. as inpipelines. V In this modified procedure, -a freshly -ground rust testcoupon' consisting "of /2 -inch diameter by 5% inches long mildsteebrodi's suspended in a 400 bea ker equippedwith a stirrer and 'placed in atemperature controlled bat-h capableo'f-maintaining-thetemperatureOfjlOQil F; test-fuel- (35O -ml.) is addedand stirred for thi rty-minutesto allow the ruest inhibitor to precoatthe-test specimen. Pa1t'(-50 ml.) of the test fuel is'gthen removed and30 cc. of dis- ..tilled .water is .added. The mixture .is .stirred forra.four- .hour-test-period. At the end of this period, the coupon isremoved, dried with; suitable solvents, inspected and rated; accordingto the following scale:

:The test conditions are substantially more severe thanordinaryconditions encountered so theresults give a clear indication ofthe eflfectiveness and amount of the novel corrosion inhibitors requiredin the particular oil tested to obtain a rating of B++ or better.

1 Pounds of inhibitor needed per 1000 barrels of hydrocarbon to obtain arating or better in the modified ASTM-D665 test. (Dry soap 1 API gravityof 62.7 Re1d vapor pressure 9.0; boiling range of 96 to 405 F.; ASTM gum2.

8 See Table I.

The reaction products of Examples I and II were added to diesel fuel andevaluated in accordance with the following static test procedure. A flatstrip of mild carbon steel A" x /2 x 5%") is cleaned with naphtha orother solventto remove grease and oil and then polished with emery clothuntil no rust or pits remain. During and after these polishingoperations the strip should be handied with a clean lintless cloth or apiece of facial tissue. After the strip has been thus prepared it shouldbe carefully wiped free of emery dust. The specimen together with 100ml. of the sample to be tested are placed in a corked 4-ounce oil samplebottle which is allowed to lay on its side at room temperaturefor 1hour. The liquid should cover the test specimen during this contactperiod. Then add ml. of distilled water, cork tightly, and shakevigorously for 2 minutes to insure water wetting over the entire stripsurface. The specimen should be tightly wedged between the cork and thebottom of the bottle to minimize breakage. The bottle is then restoredto an upright position and allowed to stand at room temperature. Thespecimen is examined for rust daily after each day the bottle is shakento replace water droplets on the specimen in the .hydroc arb on phasethat may have-been disturbed during inspection. When, percent of thespecimen exposed in the aqueous phase becomes rusted the test hasfailed. The tests are main quadruplicate and the average failure time isreported.

As shown below in TableIII, the inhibitor compound of Example I gaveexcellent corrosion protection as indicated by the passing of 642 hoursbefore 25 percent of test coupon had rusted. 'Fhe significance of thestatic test .shows the'usefulness of the inhibitorin systems where thehydrocarbon stock does not flow'past the metal surface to replenish thecorrosioninhibitor, e.g. as in -a storage tank. The diesel fuel employedhad an API gravity of 38.6, a boiling range of Y370 to 640 F. and an SUSuPounds per thousand barrels (dry soap basis).

11 Hours before 25 percent ot the area of coupon exposed to the aqueousphasehaarusted,

As previously indicated, the corrosion inhibitors of this inventioncanbe prepared by using more than the stoichiometric amount of thereactants and the excess can be included with the principal corrosioninhibitor. The following Example HI illustrates the preparation ofacorrosion inhibitor when using an excess of fatty amido diaminemono-oleate. Example IV is substantially the same preparation with theexception that a fatty diamine mono-oleate is employed rather than thefatty amido diamine mono-oleate.

EXAMPLE III 'Iwenty-five parts by weight of the mono-oleate salt of thefatty amido diamine mono-oleate mono-sulfonate by weight of oil-solublesulfonic acid (as a 10 percent concentration in its mineral base oil,300 SUS at F., acid number 16.4) were reacted at a temperature of 100 toF. A clear homogeneous solution resulted which was a 32.5 percentconcentration of the monosulfonate fatty amido di'amine salt of theoleic acid together with the excess fatty amido diamine mono-oleate.

EXAMPLE IV A mono-sulfonate fatty diamine salt of oleic acid wasprepared in the above manner by reacting 25 parts by weight of themono-oleate salt of the fatty diamine described in Example II with 75parts by weight of mahogany sulfonic acids (10 percent concentration inits base petroleum oil, 300 SUS at 100 F., acid number 116.4). Thereaction was carried out at a temperature of 100 to 120 F. and ahomogeneous solution resulted which was a 32.5 percent concentrationof'the monosulfonate fatty dia'mine salt of'oleic acid together withexcess fatty diamine mono-oleate. v

The data of Table IV below illustrate the effectiveness of the fattyamide diamine mono-oleate mono-sulfonate inhibitors containing excessfatty amido diamine mono- Table IV v M1L-L-2126o HUMIDITY CABINET TESTRESULTS Ooncentra- Average I Preparation, Weight Number CorrosionInhibitor tion Percent, of Days Dry Soap Before Basis Busting Fattyamido diamine mono-oleate 'Ex. IIL... 295 .4

IIJOIlO-SlllIOllBtB. 7

Do Ex. 11L-.. 65 .14 Do Ex. 111-... 97 21+ Mono-oleate fatty diaminemono- Ex. 295 1. 5

sultonate We claim: v c I 1. A liquid petroleum oil to which a corrosioninhibiting property has been imparted when used under high humidityconditions by the incorporation of a small but effective amount of achemical compound selected from the formulae: Y

. lei-c; H

RPS- H in which R and R represent monovalent hydrocarbon radicalscontaining from about 6 to 22 carbon atoms, R is the aromatichydrocarbon radical of an aromatic sulfonic acid and R and R aredivalent aliphatic hydrocarbon radicals containing from about 2 to 8carbon atoms.

2. The composition of claim 1 in which R is a straight chain unsaturatedhydrocarbon radical of about 16 to 18 carbon atoms, R is the unsaturatedhydrocarbon radical of oleic acid, R is the aromatic hydrocarbon radicalof petroleum mahogany sulfonic acid and R and R are tri-methyleneradicals.

3. A light petroleum distillate to which a corrosion inhibiting propertyhas been imparted when used under high humidity conditions by theincorporation of a small but efiective amount of from about .001 to 5percent by weight of a chemical compound selected from the formulae:

in which R and R represent monovalent hydrocarbon radicals containingfrom about 6 to 22 carbon atoms, R is the aromatic hydrocarbon radicalof an aromatic sulfonic acid and R and R are divalent aliphatichydrocarbon radicals containing from about 2 to 8 carbon atoms.

4. A diesel fuel to which a corrosion inhibiting property has beenimparted when used under high humidity conditions by the incorporationof a small but effective amount of from about .75 to 3 percent by weightof a chemical compound selected from the formulae:

'10 and Ii Ii n-o-rm-m-rr-m-rr-o-o-n.

in which R and R represent monovalent hydrocarbon radicals containingfrom about 6 to 22 carbon atoms, R is the aromatic hydrocarbon radicalof an aromatic sulfonic acid and R and R are divalent aliphatichydrocarbon radicals containing from about 2 to 8 carbon atoms.

5. A gasoline to which a corrosion inhibiting property has been impartedwhen used under high humidity conditions by the incorporation of a smallbut effective in which R and R represent monovalent hydrocarbon radicalscontaining fromabout 6 to 22 carbon atoms, R is the aromatic hydrocarbonradical of an aromatic sulfonic acid and -R and IR& are divalentaliphatic hydrocarbon radicals containing from about 2 to 8 carbonatoms.

References Cited in the file of this patent UNITED STATES PATENTS2,329,251 Chenicek Sept. 14, 1943 2,543,852 Jaccard Mar. 6, 19512,583,772 Gunderson Jan. 29, 1952 2,596,925 Gunderson May 13, 19522,598,213 Blair et al. May 27, 1952 2,805,135 Bell et a1. Sept. 3, 19572,839,372 Lindstrom et al June 17, 1958 2,854,324 Shen et a1. Sept. 30,1958 2,862,883 Hughes et al. Dec. 2, 1958 UNETFED fiTATES PATENTQFFICE@ETWEQATE @F @QRREQTWN Patent N0, wg osl July 11 1961 David B, Sheldahlat 3.1,,

It is hereby cw'bified that @rror appeam in ths above mumbeled pat antrequiring. eorrection and-that the. gait Letters: Patent sh-imld read.as corrected below,

Calumn 8 'line 14 for *mmmoleate nwna-sulfonate" read 0? Example I and75 parts line 35 for amide read amide column 10 lines 3 .1 t0 39 for iheR 0n the extreme right -hancl end of the structural farmula (11) read"7'- R Signed and sealed this 9th day of January 1962,

(SEAL) Attest:

ERNEST W, SWIDER DAVID L LADD Attesting Officer Y I Commissioner ofPatents UNKTFE Sums ATENTQHQE QETEEQAE @F mmm Patant Na 2 992 081 July11, 1%1

David B. Sheldahl at 31.,

It is hereby caf'bifigd that @rror appaar in tha above: num'bared patant requiring, correction and that fihe. gaid Letters Fate-mt ahmld readas corrected beloww Calumn 8 line M fer "nwsmwleate mmnasulfonate readof Example I and 75 parity line 35 far amide read amide (201mm 10 lines3432 m 39 for the R on the extreme right-inane? end of the structuralformula (11) read H1 0 Signed am? sealed Malls 9th day mi January 1962.,

(SEAL) Attest:

ERNEST SWIDER DAVID L LADD Attesting Ufificer Gommissioner of Patents

1. A LIQUID PETROLEUM OIL TO WHICH A CORROSION INHIBITING PROPERTY HASBEEN IMPARTED WHEN USED UNDER HIGH HUMIDITY CONDITIONS BY THEINCORPORATION OF A SMALL BUT EFFECTIVE AMOUNT OF A CHEMICAL COMPOUNDSELECTED FROM THE FORMULAE: